The field of the present invention relates to flying discs of circular shape which are injection molded in a single molding operation and more particularly to sport discs such as the omni-present Frisbee.RTM. brand flying disc sold by Wham-O.RTM. of San Gabriel, Calif.
Flying discs are used in many recreational activities, the most common being the game of throw and catch. Another disc sport experiencing growth in popularity is disc golf where a player throws a disc toward a basket device which serves as the "hole". Most holes are about 100 yards (60 meters) long and a player gets three "shots" or throws in order to make "par" for the hole. There are now disc golf courses throughout the United States and in many other countries. Many other sports and games are also played with flying discs, notably the game of Ultimate which is a team throw and catch game similar to soccer or football in which a team advances the disc by throwing only. The flight path precision despite adverse wind conditions and ease of throwing are key factors.
For any design of flying disc, the criteria by which the present inventor evaluates a flying disc includes (1) throwability--how easily is the disc gripped and released, (2) flight characteristics--how does the disc fly, including flight path, flight path precision, flight stability, drag, lift, ballistics, and susceptibility to flight path deflection by wind and (3) durability--how a disc stands up to wear and tear including scuffing and collisions (such as trees) and what impact such wear has on the disc's flight characteristics.
Flight stability of the disc will be described as the flight characteristic of how well the disc "holds its intended line" during its flight, particularly when thrown at higher speeds. A disc's flight path is not necessarily a perfectly straight line but actually an "S" curve. If the degree of the "S" curve is too extreme, the disc is not readily controllable and is considered "unstable". A disc that is "unstable" will undesirably turn over and fall i.e "crash") when thrown at a given speed. A thrower desires a disc to fly in a predictable pattern despite varying or high wind conditions, or when the disc is thrown at high speed (such as for longer distance throws or throws into the wind), medium speed (such as for medium distance throws or when playing catch), or low speed (such as for short throws or when putting in disc golf). A disc may still be considered "stable" despite a tendency of the disc to bank slightly to the side (right or left). In the sport of disc golf, some discs are used for that very purpose. In disc golf parlance, a disc is "overstable" if it has a tendency to bank slightly opposite to the direction of spin (i.e. slightly to the left for a right handed backhand throw) at a given speed. Similarly, a disc is "understable" if it banks slightly in the direction of spin (i.e. to the right for a right handed backhand throw) at higher speeds.
The most widely recognized flying disc is the conventional Frisbee.RTM. such as the Pro.TM. model having a flat central section and a downwardly extending rim with a blunt edge, the disc having a continuously curved transition from the central section to the rim. This design for years was considered, and for many uses is still considered, a preferred disc design. However, the conventional Frisbee.RTM. Pro.TM. model design has limitations in grip characteristics, durability, and in distance throwing or windy conditions.
The present inventor's U.S. Pat. No. 4,568,297 describes a flying disc having good throwability, superior distance and superior flight path predictability as compared to the conventional Frisbee.RTM. design. Flying discs made under that patent are manufactured and sold by Innova Champion Discs, Inc. of Ontario, Calif. These discs have a low profile, a triangular rim (the so-called "beveled edge") providing increased mass at the rim, and a flexible central section. The Innova discs have set world records for distance, have revolutionized the sport of disc golf and are the discs of choice for professional disc golfers worldwide.
The present inventor has recognized there is still room for additional improvement in the design of flying discs.